Testing TRIM

A firmware update gives you TRIM support, but we should probably test to make sure it's actually working.

First up, the Intel X25-M G2 with the TRIM firmware. I ran a 4KB random write test across the entire 80GB LBA space for five minutes. I ran the test again afterwards and recorded the average transfer rate for each run:

4KB Random Write, IOQ=16

Run 1

Run 2

Intel X25-M 80GB TRIM Firmware

37.9 MB/s

13.8 MB/s

As expected, performance goes down as the drive fills up. The second run is much slower than the first.

Now look at the two runs if we format the drive in between. The format under Windows 7 triggers a TRIM of all invalid data, meaning all the jibberish we generated in the first run is gone and the second run now runs at full speed:

4KB Random Write, IOQ=16

Run 1

Run 2 after Format

Intel X25-M 80GB TRIM Firmware

37.9 MB/s

38.0 MB/s

Obviously you don’t usually write a bunch of garbage to your drive then format and repeat, but we’re trying to confirm that TRIM works here; it does. Windows 7 will actually take noticeably longer to format a drive that supports TRIM and has data on it. It still completes in less than 30 seconds on these SSDs, but it's a lot longer than the few seconds it used to take before TRIM.

This confirms that TRIM works on a format, but what about if you delete a partition? To find out I created a partition on my X25-M G2, filled it with data, deleted the partition and ran my 4KB random write test across all LBAs. If deleting a partition forces TRIM I should see new-performance out of the G2:

4KB Random Write, IOQ=16

Run 1

Run 2 after Deleting Partition

Intel X25-M 80GB TRIM Firmware

37.9 MB/s

17.9 MB/s

Performance drop. Formatting a partition causes the contents to be TRIMed, but just deleting a partition doesn’t. This means if you accidentally delete a partition you can still retrieve your data, however there’s no way to go back from a format.

What about file deletion? I performed the same test. Created a partition, filled it with garbage but then deleted the garbage before deleting the partition and running my 4KB random write test. Deleting data should force a TRIM:

4KB Random Write, IOQ=16

Run 1

Run 2 after Deleting All Files

Intel X25-M 80GB TRIM Firmware

37.9 MB/s

40.4 MB/s

Indeed it does. You no longer have to worry about performance dropping over time. When you delete a file it’ll eventually be nixed on the SSD as well. Below we have the actions that will force a TRIM of data under Windows 7:

Windows 7

File Delete

Partition Format

Partition Delete

TRIM?

Yes

Yes

No

Formatting your drive now actually does something. You no longer have to boot to DOS and secure erase your SSD before installing Windows, just quick format the partition before installing Windows 7.

I performed the same tests on an Indilinx MLC based SSD, this time a SuperTalent UltraDrive GX with the 1819 TRIM-enabled firmware. The results were identical:

4KB Random Write, IOQ=16

Run 1

Run 2

After Format

After File Delete

SuperTalent (Indilinx) UltraDrive GX TRIM Firmware v1819

17.8 MB/s

14.1 MB/s

17.8 MB/s

17.8 MB/s

We have TRIM working on both Indilinx (from SuperTalent/OCZ) and Intel drives. Sweet.